I am not partial to the “calories in, calories out” model of fat loss and lean body mass gain.

This doesn’t mean that energy intake (i.e. calories) don’t matter.

Nobody’s body breaks the laws of thermodynamics. It just seems that way sometimes.

So energy balance absolutely matters.

The quantity of energy you take in and excrete is important.

But focusing on just calories in / calories out leads to dumb shit like “100 Calorie Snak Paks!”; drunkorexia (i.e. not eating so you can drink more and not gain weight); fake foods (remember Olestra?); and other forms of “calorie bargaining”.

It also leads to OCD calorie counting, asking how many calories are in a Tic-Tac, trying to “burn off calories”, getting upset about what the calorie display on your exercise machine days, and various related unproductive shenanigans that don’t leave you any more sane or healthy.

What’s interesting here is that the researchers stipulate “quality protein”. What the heck does that mean?

Let me explain the concept of essential amino acids (EAAs).

Essential amino acids and protein quality

If there’s one thing Nature does real good, it’s make proteins. (Actually, Nature does lots of things real good.)

Oh how organic systems love their proteins. You’re a big pile of protein, from your hair to your toenails.

The building blocks for proteins are amino acids. There are lots of amino acids out there.

Sure, we love ’em all, but there are some that we really need — these are known as essential amino acids.

There are also amino acids that are conditionally essential, which means that sometimes we need them more than others. Frinstance, glutamine is a conditionally EAA — we need more of it during times of physical stress, which is why it’s often included in post-surgical nutrition.

Now, what you’re looking for in your diet is a good assortment of these EAAs, and generally (unless you have some kind of intolerance or genetic inability to metabolize certain AAs) getting some of the conditional AAs doesn’t hurt either. Bone broths, for instance, are rich in glycine. (And they taste great! So win-win.)

Some proteins are more equal essential than others

Problem is that not all protein sources are created equal.

Just because something “contains protein” does not mean that the protein source is optimal.

Sure, we’re scavengers so we will grab ‘n’ go whatever we can get our greasy little protease enzymes on — we can extract protein from darn near anything edible.

But that protein may not be our best choice.

Frinstance, vegetarians often opt for beans/legumes, grains, and nuts as protein sources. (And others of you like to delude yourself that peanut butter is a “good protein source”. Hey man, I get it. Nothing beats scooping out that buttery goodness and feeling morally righteous and nutritionally justified as the silky, sexy, salty, peanutty velvet melts into your soft palate. Unnnngghhh.)

Now, these protein sources aren’t “bad” or “wrong”. They’re just not optimal.

Let’s compare.

Here’s a sample of protein ranking according to the PDCAAs score. (Don’t worry about the acronym. Just get the idea.)

The PDCAA scores proteins on two things:

our amino acid requirements, and

how well we can digest these particular proteins.

The higher the number, the better-quality (for us) the protein in terms of giving us the amino acids that we need.

1

casein (milk protein)

1

egg white

1

soy protein

1

chicken

1

whey (milk protein)

0.9 to 1

fish

0.97

turkey

0.92

beef

0.91

soybeans

0.78

chickpeas

0.76

fruits

0.73

vegetables

0.7

Other legumes

0.59

cereals and derivatives

0.42

whole wheat

Lab vs real world

I should point out that theoretical digestibility doesn’t always correlate to real-life digestibility.

Although, for instance, whey and casein are highly ranked, many folks actually can’t digest dairy well, and in fact consuming casein/whey is a source of other health problems. Same deal with soy — if you rely on soy as your major protein source you are in for some serious issues. And of course, if you’ve read Fuck Calories, you’ll know how I feel about wheat.

Indeed, some researchers have pointed out that the PCDAAs may over-value certain foods if it looks only at amino acid availability, noting that the PCDAAs ignores the real-world protein quality of the “protein sources which may contain naturally occurring growth-depressing factors or antinutritional factors”.

What this means is that we have to look at the big picture.

How does a given food actually behave in a real human body?

Also note that not all of these are whole foods.

Casein, whey, and soy protein powders are industrially processed foods that require an elaborate production chain.

You know my thoughts on industrially processed foods, which is that in general we should avoid most of them. And unless we’re hardcore bodybuilders, we don’t just eat “casein”, we usually eat something like “cottage cheese”, which contains both whey and casein.

But anyway, just get the general picture here. Some foods are higher in essential amino acids than others.

This is what the researchers mean by “quality protein”. More EAAs per gram of food, better protein quality.

Better protein quality means a leaner body?

The Coles Notes version here is that a higher intake of quality proteins is correlated with a smaller waist size, and by inference a leaner body.

Now, you could say the sample is too small to be of use, and that this effect is simply correlation not causation. You would be correct on both counts from a methodological standpoint.

But this general trend (abundant protein = you get lean & strong) has been confirmed across a zillion other studies.

So again, let’s talk lab vs. real world.

I can tell you from my observation of hundreds of clients (yes, real people in the real world, just like you) that it’s very, very hard to get lean and strong, to stay robustly healthy, and to perform well athletically on a low-quality, low protein diet.

Period.

There are always a few rare outliers who claim to kick ass while living on twigs and sprouts, and more power to ’em.

Likely, those folks are not you.

Conversely, for most folks it’s a lot easier to feel energetic, full, and psychologically satisfied — and get lean — on a diet that includes lots of high-quality protein.

Mo’ protein, no problems.

If you don’t incorporate high-quality protein sources into your diet (and let’s be honest, I mean eating something that is an animal or was made by an animal), you’ll likely find it more challenging to get and stay as lean, healthy, and strong as you would like, and you’ll have to rely more on heavily processed foods such as protein powders to bring your intake up to snuff.